He is doing it to see how far he can push you and when you are tired and worn out (like me with 3 kids) its easy for him to get to you.
If you can and I know its hard (but it works for my son) go over board with praise for good behaviour, activities he has done however little ie: saying please, thankyou, tidying up toys show him and tell how well he has done. My son's little chest literally puffs up when I do this.
When he is naughty give him 1 warning and say that if he does it again you will give him time out on his own ie: naughty step.
The best bit of advice is BE CONSISTENT AND ALWAYS FOLLOW THROUGH!!!
If he knows that you mean business then he will stop pushing you.
When I started this with my son he thought it was a big joke all the time and just carried on playing up. he soon got the message when my other kids got to go to the park with their dad and he stayed to clean the bathroom with me!!
Good Luck- just remember its all for your attention.