Does a 16 yr old child have the right to decide that she wants to live with step father after her mother and him have divorced? He has been in her life since age of 3 and he is the only Father she has ever known. She has told him she is going to run away if she can't live with him, Mother and him are not on good terms. Does he have any rights grant her wish?

First a 16 year old does not have a right to choose between their bio mother and bio father. They may tell the court where they want to live but the judge will decide.

If the step dad did not adopt, he has no rights what so ever,
In fact he will have to return the girl if she runs away and moves there, or he can be charged with either kidnappng or at least interfering with custody.