I am sorry for your loss, 16 is very very young age to go.
All of us belong to God. When we were born, God performed a miracle and created you and me and your son. So first, we must understand that what we get from God is on loan until such times as he wants them/it back.
Just for a moment, instead of wondering why or if God took your son, think about what your son meant to you while he was here. Think about all that you liked and enjoyed about your son. Think about the joy he brought. And if he was in any pain or was suffering or his life was in danger, he is now in a better place. God is a loving God, read about him in St. John 3:16 - For God so loved the world, that he gave his only begotten son, that whosoever believeth on him shall not perish, but have everlasting life". God gave his son, Jesus when he was 33 (the bible says), to die for us, to die for our sins - now that's a loving God.
I lost my brother, he was 41 years old (too young to die) this May, he was murdered. -- I am sad about that, but I have used his death to learn and be grateful for the time I had with my brother and the joy he brought to our family.
My prayers are with you! Seek to know God and learn about him by reading the bible.