None of the clients generates  less than  a block (50 btc). But this event is very-very rare: you can estimate your chances here:
http://www.alloscomp.com/bitcoin/calculator.php .

So, you have to join a mining pool, there the risk&profit is divided between users & mine with a specialized program if you want to get your own coin.
IMO, now it's easier & in many cases cheaper just to buy

Good luck!