Naetuir is right – Bard is exactly what you're looking for here, even to the point of being a bit of a joke. Using "Fighter: melee dps Wizard: buffing Thief: skills" as the main set of requirements, lets see what we can do to build a straightclass Bard Elan, as compared to his needlessly complicated twin brother Nale. (Who's a wizard, not a sorcerer, as per the suggested build in the question.)
Damage Per Round
A fighter's melee dpr (damage per round, as apposed to damage per second. A pedantic detail, but a more correct one) comes from three things. First, the favourable base attack bonus (hereafter referred to as BaB) progression means that he will be able to reliably hit his target. Second, the martial weapons feat allows him to pick a weapon that deals a lot of damage. (I think greatswords win in terms of raw average damage, ignoring double weapons.) Third, they get a large number of bonus feats, which they can then turn in to more damage and BaB. There are three BaB progressions used by the different classes, and it happens that fighters have the fast track, rogues and bards have the medium track, and wizards have the slow track. So what's the problem with using a fighter in this? Nale should be beating his bardic brother in all three categories, since bards don't have the proficiencies, feats, or BaB that fighters do.
The problem is, assuming Nale is trying to stay even in all three classes, (which I'm assuming you are, since you want to be a "jack of all trades") that at level three Nale will have a level of each of his three classes. He'll get a +1 BaB for being a fighter, which stacks with the +0s he got from being a wizard and a rogue, netting him a total BaB of +1. Elan, on the other hand, gets +2 for being a level three bard. At level 6, Elan the Bard has a +4 BaB for being a 6th level bard, and Nale has a +2 from second level fighter, +1 from second level wizard, and +1 from second level rogue, giving him a +4. At level nine, Elan has +6/+1, getting his second attack, and Nale has +3 from being a third level fighter, +2 from being a third level rogue, and +1 from being a third level wizard, for a +6/+1, exactly the same. This actually continues through until epic levels- after level six, the fighter has caught up and stays caught up in terms of the attacks, but never gets better. It basically depends on which order Nale takes the wizard/fighter/rogue in, as he might pull ahead by 1 for a level, only to fall behind by 1 later. (BaB progressions pulled from SRD) Straightclass bards have a higher or equal BaB than a fighter/rogue/wizard cross, right up through epic levels.
Nale still has that greatsword, which does more damage. This is anecdotal evidence, but I don't tend to swap weapons very often in DnD. I use whatever I can until I can afford the weapon that I was building for, and often I start with it due to starting gold. (The greatsword costs 50 gold according to SRD and the bard starts with an average of 105gp in Pathfinder. If by level three you can't get ahold of a basic weapon, the DM is probably messing with you.) So having the ability to use all martial weapons isn't actually all that important. Elan the bard can take a martial weapons proficiency(greatsword) at level one, buy it with his starting gold, and never look back.
So what about feats? A fighter gets a bonus feat every other level. There are a whole lot of perks that you can get from extra feats, even if you're just stacking weapon focus/weapon specialization/greater weapon focus/greater weapon specialization, (which, together, give you a +2 to hit and a +4 to damage, which goes a long way towards evening the playing field against Elan. Normally a character only gets a new feat every three levels, so getting an extra feat and a half every three levels (Averaging a little here- a fighter gets three bonus feats and two normal ones every six levels, a bard just gets the two normal feats.) Wizards also get bonus feats, every five levels, but these are restricted to a different list of feats and will not help with DPR. The downside is, rogues don't get bonus feats (and wizards don't get helpful ones) so since Nale is only taking one level of fighter every three levels, he gets a bonus feat every six levels. Instead of an extra feat and a half every three levels, he gets half a feat every three levels. That's not useless, but it will not allow him to run through the weapon focus chain fast enough for it to make up for the problems with his BaB progression.
Basically, a bard wins on BaB, ties on weapon damage with the investment of a single feat, and only getting one fighter level every three character levels slows the bonus feats down so much that they fail to make this a preferable path for DPR.
Wizards have a much better spell progression than bards. Every two levels, they get a new spell level, and all else being equal they'll have an extra spell at each level per day. But they fall prey to the same problem fighters have, in that they only actually get those levels a third as often as they should. At level three, a straightclass wizard should have access to a second level spell, whereas the bard only has a first level spell. Problem is, Nale is only a first level wizard at level three, which gives him... *drumroll*... a single first level spell. Oh, and three cantrips. The exact same loadout that the bard has. This is actually as good as Nale is going to get it, because unlike the fighter, he doesn't stay even with with Elan – he starts falling behind and fast. At level six, the bard is a spell level ahead. By level fifteen, Elan is two spell levels ahead. A wizard's chief advantage in spells should be that bards only get up to sixth level spells, whereas wizards can cast up to ninth level spells. The problem is, the Nale will never get to do this- assuming we aren't going epic, he'll only be a 7th level wizard at most when we stop, giving him fourth level spells. That's a large gap in power. Wizards do have a larger list of spells, but when it comes to buffs, bards have all the important ones, plus the ability to cast healing spells (which wizards can't) and don't need to prepare spells for the day. Given that buffing and healing tends to be more reactionary, the ability to change your plans is invaluable. The one bonus feat you would get as a wizard does not make up for being two spell levels behind.
Bards get 6 skill points per level, plus intelligence. Rogues on the other hand get 8 skill points per level, plus intelligence.(SRD and SRD again) So, clear advantage there. But again, every three levels! Fighters and wizards get 2 plus int, and a massively reduced list of class skills. Assuming a +0 to intelligence, after three levels Elan will have 18 skill points, and Nale will have 12. (Ignoring the 4x multiplier for first level.) This gap will continue to get wider as they get higher level, and remember, Elan the bard has Inspire Competence, and while he can't use it on himself, he can use it on an ally and have them aid another.
So, moral of the story; Don't run three base classes. You keep missing out on the things which make you stronger. Play a bard, who can do pretty much everything they can. (Except sneak attack, but hey, life isn't perfect.) But you asked for a build, so, here it is, in general form since I don't know the rulebooks you have, the other player's roles, or the method of stat generation...
To start, play a human. That will give you the extra feat and skill points to keep up with the fighter and rogue in the initial stages where Nale hasn't started suffering for his lack of focus. Put the bonus feat from being human towards whatever weapon you plan to use, probably a martial weapon. (Greatsword, as I mentioned above, combines nice base damage with a decent critical rate.) I would recommend using the next feats for Quick Draw, as you're going to need to bardsong and then enter combat (or you could always take perform vocal and just sing, if theme isn't as important to you) or with an eye for getting Improved Critical later, if the game will last that long. Statwise, first make sure you have enough charisma that you can cast all your spells up to whatever level you plan to reach eventually- so 16 is as much as you possibly need, probably less as you can increase that as you level up. Strength and intelligence are your highest priorities after that- strength for the attack bonus and damage, and intelligence for skills. Any extra points should be put into dex for extra AC, and con for extra hit points. Use wisdom as a dump stat. Skill wise, keep your spellcraft and perform checks maxed, and place the others however you want. Spellswise, get the +4 buffs as soon as you can (Bull's Strength, Cat's Grace) and the cure spells wouldn't go amiss.
There ya go. A bard with a decent hit and damage rate, lots of skills, and enough spellcasting to keep the party in shape. Just be careful- any one of those classes straightclassed will be able to beat you as long as it's their kind of combat. The bard is truly a jack of all trades, but that does mean they are the master of none.
Note: I should probably look up the actual references in the Players Handbook, but I loaned my copy to another player. Next time I get my hands on it I'll fix the footnotes, but the SRD is usually pretty good.