use Regexp::List ();

my @keywords = ("keyword1", "keyword2", "keyword3");

my $pattern = Regexp::List->new->list2re(@keywords);
#my $pattern = join('|', map quotemeta, @keywords);  # Alternative

while (<SEARCHFILE>) {
   if ($_ =~ $pattern) {  # or just: if (/$pattern/) {
      print $_;           # or just:    print;
   }
}