if($i > 4) { $i = 0; }
<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel" aria-hidden="true">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<h5 class="modal-title" id="exampleModalLabel"> <p class="request_header">Оставьте заявку</p>
<p class="request_subheader">Для проведения расчетов</p></h5>
<button type="button" class="close" data-dismiss="modal" aria-label="Close"></button>
<span aria-hidden="true">×</span>
</button>
</div>
<div class="modal-body">
<?php echo do_shortcode('[contact-form-7 id="" title=""]'); ?>
</div>
</div>
</div>
</div>
</div>