It can be done, but I'm not sure that this is "simplifying" the code!
 Code:
$sStringsToSearch="ab,bc,bcd,d"
$s="abcd"

"Checking if string '"+$s+"' contains all the sub strings from '"+$sStringsToSearch+"'"+@CRLF
"'"+$s+"' result: "+Execute("Exit InStr('"+$s+"','"+Join(Split($sStringsToSearch,","),"') AND InStr('"+$s+"','")+"')")+@CRLF


I'd probably just use a loop for readability.