What can I do if my cat scratches and bites me?
You don't have enough information for a good answer. Is he neutered? Unneutered males can become aggressive and nasty, so getting him neutered will correct that. Is this a kitten? Kittens taken from their littermates too soon (before about 12 weeks) have not learned how to play properly and will scratch and bite. Pick him up, HISSSSS loudly, then put him down and totally ignore him. That is what his littermates would do. If you are tormenting the cat, like holding it while he's struggling to get down, he is going to scratch and bite. Do you play roughly? Same thing. Has this become a new behavior? It can signify that the cat doesn't feel well, or you are touching a spot that causes pain. More information - and you will get better answers.
Clip his nails. You can pretend he's hurting you by making a loud noise he'll stop as cats observe reactions.
Bite it back.
The cat might need a distemper shot. You should take it to the vet.
If you are mistreating the animal or teasing it, you need to stop doing so.