my $kw1="user.alert";
my $kw2="user.crit";
my $kw3="user.err";
my $ukw1="WLAN";

#....

if (
  $lines !~ /\Q$ukw1\E/
  and (
    $lines =~ /\Q$kw1\E/
    or $lines =~ /\Q$kw2\E/
    or $lines =~ /\Q$kw3\E/
  )
) 
#....