Hi S.,
Without knowing more, it sounds like your son is very attached to your husband and really values what your husband thinks and says, and is most interested in being with Dad and pleasing him. You could try to use a reward system (happy faces) that focuses on listening and following simple directions fom you. At first it would be easy. Each time he follows a simple and easy direction he would get a happy face. Your son would need to earn a small number at first (1-3)and then more happy faces as time goes on or it would get more difficult to earn as time goes on (every 3rd direction followed earns a happy face). Once he earns the alotted number each day, the prize could be some special activity or prize with your husband, or preferrably both of you. Another effective prize might be something really special and fun that happens with just you to help make being with you and pleasing you more rewarding. To start it off though, the prize may need to involve your husband as well since that seems to be what your son finds the most valuable right now. The prize doesn't have to cost a lot of money like trips to the toy store, but it should be something he would really enjoy. Both you and your husband should explain the rule and what he can get and review it with him each day. You may even want him to earn a few times a day (1x in the a.m. and 1x in the p.m.) to make it really effective and then fade the number of earning times as his behavior improves. Make sure he doesn't have to wait too long to earn his prize or this will not be effective. He should get his prize as soon as he gets the last happy face to start, and then as he learns what is expected he can wait a little while longer. Also, if there is a delay between the last happy face and the reward it gives him time to make an error, like not follow a direction and then you will have to take one away and this could be difficult in the beginning. This can be used at school too.
I hope this helps and wasn't too long!
Take care,
J.