use HTML::Parser;
use Data::Dumper;

my $search_term          = qr/\b something here \b/ix;
my @tags_to_search       = qw[ title h1 h2 h3 h4 h5 h6 a li p pre img ];
my @attributes_to_search = qw[ alt href ];

my %seen;
my $last_seen_tag;

sub start {
    my ($tagname, $attr, $text) = @_;
    $last_seen_tag = $tagname;

    for (@attributes_to_search) {
        $seen{$_} += $attr->{$_} =~ m/$search_term/g
            if $attr->{$_};
    }
}

sub text {
    my $text = shift;
    $seen{$last_seen_tag} += $text =~ m/$search_term/g;
}

my $p = HTML::Parser->new( api_version => 3,
                           start_h => [\&start, "tagname, attr"],
                           text_h  => [\&text,  "text"],
                           unbroken_text => 1,
                           report_tags => \@tags_to_search
                         );

$p->parse_file("foo.html");
print Dumper \%seen;