WP_Query based on a custom field result

Question

I would like to know if there's a way to do a query filtered by a custom field result. In this case, I have 6 posts I would like to retrieve, but only if they have "true" selected in a custom field I've previously created. The name of the custom field is called "featured".

Here's my code

<?php
$recentPosts = new WP_Query();
$recentPosts->query('showposts=6');
?>
<?php while ($recentPosts->have_posts()) : $recentPosts->the_post(); ?>
    <li>
        <?php if ( has_post_thumbnail() ) {?>
        <div class="post-thumb-140">
            <a href="<?php the_permalink() ?>"><?php the_post_thumbnail( 'post-thumb-140' ); ?></a> 
        </div> <!--post-thumb-->
        <?php } ?>

        <a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a>
    </li>
<?php endwhile; ?>

I've checked WordPress documentation on possible WP_Query arguments, but there are no filters based on a custom field.

Any ideas?

Answer 1

Here's the corrected code, thanks @Milo!

<ul>

<?php
    $recentPosts = new WP_Query();
    $recentPosts->query('showposts=6&cat=1&meta_key=ticker&meta_value=yes');
?>
<?php while ($recentPosts->have_posts()) : $recentPosts->the_post(); ?>
    <li>

    <?php if ( has_post_thumbnail() ) {?>
    <div class="post-thumb-140">
    <a href="<?php the_permalink() ?>"><?php the_post_thumbnail( 'post-thumb-140' ); ?></a> 
    </div> <!--post-thumb-->
    <?php } ?>

        <a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a>
    </li>
<?php endwhile; ?>

</ul>