$pat1="field";
$pat2="f.i.e.l.d";
$pat3="the";
$str = "There are many soccer fields in England - f1i2e3l4d";

while($str =~ m/($pat1|$pat2|$pat3)/ig){
   print "Found '$1' from pattern ??\n";
}

##</code><code>##

Found 'The' from pattern ??
Found 'field' from pattern ??
Found 'f1i2e3l4d' from pattern ??

##</code><code>##

Found 'The' from pattern 'the'
Found 'field' from pattern 'field'
Found 'f1i2e3l4d' from pattern 'f.i.e.l.d'