Change the_permalink to custom field URL

Hi,

I’m using a theme with an integrated portofolio. I would like to change the link of the portfolio to a custom URL instead of the_permalink.

Currently the code that looks up the_permalink looks like this:

<a href="<?php the_permalink() ?>" class="ci-keyimage-link" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>">

Is it possible to make a change to the code so WordPress gets the URL from a custom field instead of the_permalink field?

Full code:

<?php
    $options = get_option('ci_theme_options');
    $options_homepage = get_option('ci_homepage_options');

    if(isset($options['ci_portfoliokeybgcolor']) && $options['ci_portfoliokeybgcolor'] != '') {
        $ci_portfoliokeybgcolor = "background: #".$options['ci_portfoliokeybgcolor'].";";
        print "
            <style>
                a:hover .ci-cover {background-color: #".$options['ci_portfoliokeybgcolor'].";}
            </style>
        ";

    } else {
        $ci_portfoliokeybgcolor = "";
    }

?>
<div class="ci-content-positioner ci-content-positioner-no-top ci-content-positioner-no-bottom">
    <div class="ci-separator-3"></div>
    <h3 class="ci-hl-portfoliosection">
        <?php
        if(isset($options_homepage['ci_portfoliosectionhl']) && $options_homepage['ci_portfoliosectionhl'] != '') {
            echo $options_homepage['ci_portfoliosectionhl'];
        } else {
            echo __( 'Recent work', 'ciframework' );
        }
        ?>
    </h3>
</div>
<ul id="ci-source" class="ci-portfolio ci-portfolio-overview">
    <?php
    $count = 1;
    $query = new WP_Query();
    $query->query('post_type=portfolio&posts_per_page=-1');
    if ($query->have_posts()) : while ($query->have_posts()) : $query->the_post();

		$ci_portfolio_meta = get_post_custom($post->ID);
		$keyimageurl = $ci_portfolio_meta['ci_portfolio_meta_keyimg_1'][0];

		if(isset($ci_portfolio_meta['ci_portfolio_meta_keyimg_2'][0])) {
			$keyimagezoom = true;
			$keyimagezoomurl = $ci_portfolio_meta['ci_portfolio_meta_keyimg_2'][0];
		} else {
			$keyimagezoom = false;
		}
		?>
		<li id="entry-id-<?php echo the_ID(); ?>" class="ci-portfolio-entry" data-id="<?php echo the_ID(); ?>">
			        <?php
			        if($keyimagezoom) : ?>
						<a href="<?php echo $keyimagezoomurl ?>" class="ci-keyimage-link ci-colorbox">
							<div class="ci-cover ci-zoom-cover">
							</div>
    				        <h2 style="<?php echo $ci_portfoliokeybgcolor; ?>"><?php the_title(); ?></h2>
					<?php else: ?>
						<a href="<?php the_permalink() ?>" class="ci-keyimage-link" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>">
							<div class="ci-cover ci-detailpage-cover">
							</div>
    				        <h2 style="<?php echo $ci_portfoliokeybgcolor; ?>"><?php the_title(); ?></h2>
					<?php endif; ?>
					<img src="<?php echo $keyimageurl ?>" class="ci-keyimage" alt="<?php the_title(); ?>" />
				</a>
			</li>
		<?php endwhile; ?>
	<?php endif; ?>
	<div class="ci-clear"></div>
</ul>