Both of these orders can only be made by a court.
If social workers have applied for a Care Order for the child, you should apply to the court which is dealing with the case. You would have to show the court that the order you wanted would be better for the child than the Care Order the social workers wanted.
If social workers haven’t applied for a Care Order, you can just apply directly to the Family Court where you live for the order. If you are applying for a Special Guardianship Order, you should write to the social workers three months before, to tell them formally what you are doing. This gives the social workers time to write a report, telling the court whether they think you should get the Special Guardianship Order.