I think you want to replace:

$results = $ua->request($req)->as_string; #grab the results
[download]

with:

$results = $ua->request($req)->headers_as_string; #grab the results
[download]

When I ran your snippet, it printed out the whole response, not just the headers.

update: I used this in the past:

use strict;
use LWP::Simple qw(get head);

my $url = 'http://www.w3c.org';
print head($url)->{_headers}->as_string;
[download]

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