It's perfectly normal puppy behaviour. They are teething and that involves on your hands and arms and clothing. All pups are like this, nothing to be worried about.
When he bites, start now and stick a chewtoy in his mouth. Instead of just saying "NO!" just stick a toy in his mouth and sooner or later he will get the picture.
When he bites, start now and stick a chewtoy in his mouth. Instead of just saying "NO!" just stick a toy in his mouth and sooner or later he will get the picture.