many photographers like to stop the shutter button from activating AF, and instead use a rear button to activate AF, thereby separating the two actions
Menu > Custom Settings > Pre-AF > Off (this is pretty useless anyway and just wastes battery life - similar to Olympus “Fulltime AF”)
Menu > Custom Settings (Cogs 6) > Custom Key Settings > AEL Button > AF On
Menu > Custom Settings (Cogs 6) > Custom Key Settings > AF/MF Button > AF/MF Ctrl Toggle
then to have the AEL button function as AFL button (BUT ONLY in AF mode, not in MF mode unfortunately), choose Menu > Custom Settings (Cogs 4) > AF w/shutter > Off and just set it back to ON when you want the shutter button to do AF - unfortunately there is no way to assign this to a button - so there is no quick way to switch this mode
you may wish to assign C3 to centre AEL Toggle to create an exposure lock mechanism on centre spot
you may wish to assign Centre Button, or C1 or C2 to Focus Settings which allows moving AF point around in AF mode and magnify in MF mode
unfortunately, this is no where near as nice a solution as the Olympus solution which allows you to be in MF mode and the rear button works as AFL, but when you go to AF mode, the rear button works as AEL and the shutter works as AF - very clever and handy!