How do I get my toddler to stop hitting/smacking/biting

My son is 18 months old now & has such a bad habit of biting & hitting. Especially if he doesn’t get what he wants it if I tell him no. He literally ran up to me today, and punched me right in my lip and made me bleed & bit me the other day leaving a bruise because I took him out of the tub & he wasn’t ready to get out. now of course I discipline him but I feel like no matter what I, nothing works. My daughter is due in 45 days & I don’t want him to hurt her.. I’m overwhelmed with how bad he’s been lately