16.04 does not support flgrx and steam will not launch without it apparently, i have used the;
LD_PRELOAD='/usr/$LIB/libstdc++.so.6' DIAPLAY=:0 steam workaround but for me its kind of annoying to have to have a terminal running in the background, i have tried searching a bit but all are work arounds like the one above and the search is getting very frustrating.