use HTML::Entities qw( encode_entities );

sub text_to_html {
    my $terms = $_[1];

    my ($terms_pat) =
        map "(?:$_)",
        join '|',
        map quotemeta,
        @$terms;

    ( my $html = $_[0] ) =~
        s{
            ( (?: (?!$terms_pat). )* )
            ( $terms_pat+ )
        |
            ( .+ )
        }{
            defined($1)
                ? encode_entities("$1") .
                  "<b>" . encode_entities("$2") . "</b>"
                : encode_entities("$3")
        }xseg;

    return $html;
}

print text_to_html("best car wash & repair!!", [qw( car repair )]);