You are doing preload for the screen this way. This will not work.
What you proably want is eg server.sh:
and then just launch that from screenPHP Code:
#!/bin/bash
export LD_PRELOAD="$HOME/cod2_1_3/libcod2_1_3.so"
PARAMS="+set fs_game ..."
"./cod2_lnxded" "$PARAMS"
PHP Code:
screen sh server.sh