My weanling colt is acting up?

So I've got a 4 month old weanling colt that I'm working with and he's acting up. He tries to paw at me, kick me, and bite me. When he does I smack him with a broom handle and it seems to help for a while but then he does it again. We sold his mom the day after he was born and were bottle feeding him twice a day until about a month ago because he was just such a pain to feed. It took him a few days to start eating hay but now he eats it no problem. I'm trying to sell him so I need to get him to stop all this crap. I've got some people coming to look at him this weekend and I don't want him doing all that while they're there.