go here and click the version cheat/trainer you want ...
m0001.gamecopyworld.com/.../pc_stalker_shadow_of_chernobyl.shtml
u jsut download the trainer - dubble click the trainer file - then load the game and click the corresponding numpad key for the cheats to activate - there is like infinite health armor ammo - imune to radiation which u wanted
and others and a money cheat as well
hope i helped xD