Sounds like the 'only child syndrome!"
You need to set guidelines, as he does understand. You need to give him a time out for continual bad behavior. The rule of thumb is one minute per birth year, (i.e., 2 minutes for a two year old). This takes patience. If he leaves the corner, make him return. Sit him on a chair and explain why this is happening. When speaking to him, get at his level, don't talk down to him. Maintain eye contact.
Also, check out your husband's behavior with him. Does he implement discipline? If so, this is the reason his behavior is different while around him.
As to him hanging on you, you should engage him in a few educational toys, wooden puzzles, toys that will make him think and occupy his time and help develop his skills. Patience is virtue!
For other tips, try and catch a few episodes of SuperNanny on the ABC network.
Good luck!

