dependent child visa

[voila]

Hi there,
I have a very important an urgent question, any advise would be appreciated. The problem is following, my nephew (16yrs old) comes from a non-Eu country (Balkans), his father (my brother) was killed during the was and mother has abounded him a year later. Since then (age 2) myself and my parents looked after him. I came in uk in 2008 to join mu husband.Bbecause my mother has passed away in 2012, the nephew lives with my father (70yrs old). I am trying to find out which is the quickest way to bring my nephew to UK to live with me and in UK in permanent basis. I am naturalised citizen while my husband is born British and we are also able to financially support him in UK without any recourse to public funds. The nephew has been to visit us 3 times in UK in visitor visa. Can you please advise..?thanks