<?php
$args = array(
	'meta_query' => array(
	'relation' => 'OR',
		array('key' => 'unsold'),
		array('key' => 'booked'))
 );
$firstposts = get_posts($args);

$args = array(
	'meta_key' => 'sold'
 );
$lastposts = get_posts($args);

$mergedposts = array_merge( $firstposts, $lastposts );

$post_ids = array();
foreach ( $mergedposts as $mergedpost  ) {
$post_ids[] = $mergedpost->ID;
}
// remove duplicates
$unique_id = array_unique($post_ids);

$args = array('post__in' => $unique_id);
$the_query = new WP_Query( $args );

// The Loop
while ( $the_query->have_posts() ) : $the_query->the_post();
// rest of loop
endwhile;
?>