WordPress WP_Query with just sticky posts - page.php or index.php template

index.php

<?php
/**
* WordPress WP_Query with just sticky posts - page.php or index.php template
**/

get_header(); // loads header.php template ?>

<?php $custom_query = new WP_Query('posts_per_page=1');  ?>

<div id="wrap-sample" class="blog-sample clearfix">   
	 <?php
	// Loop through $custom_query posts
    while ($custom_query->have_posts()) : $custom_query->the_post();
        get_template_part( 'content', get_post_format() );   
    endwhile;        	
    ?>           
</div><!-- /wrap -->

<?php wp_reset_postdata(); // reset the query ?>

<?php get_footer(); //get footer.php template ?>