Most "humanoid" races, and even some non humanoid ones can be played, if you have a willing GM. the catch is that the GM has to really be able to look over the character and make certain decisions, which the player has to go with. I've played a Centaur in Pathfinder before with no problem. The creatures book says it has +8 strength, which I later found was terribly overpowered, but awesome. An Orc should similarly have stats in one of the books, and you can likely use those. But... You have to know your GM. I can't stress that enough. If this friend who says it's not in the book so you can't play it is running your game, then no, you can't play it. Otherwise, don't make it until you ask. You may be allowed, but you don't necessarily determine what that means, as there aren't set rules for it, and the GM is the one who gives the final OK.