What is taken into account when a father wants full custody of a child?How do the courts decide upon this?

Child already visits with dad from Fridays to Sundays. Now he feels he wants the child full time. He works full time and lives with 2 men in an apt. The child's mom has an apt with her daughter and can provide a better home for her son.Grandmom heps transport child to and from school each day.Mother does not have a job right now. She is on welfar. How will this affect the courts decision as to the best interests of the child. The mom does not want the dad to have full custody. He sees him whenever he wants now. - Is this your question? Add additional information