I was a little unclear on what the problem here is. But this should work if you use Chtml::htmlbutton.
<?php echo CHtml::htmlButton('<i class="glyphicon glyphicon-plus"></i> ' . Yii::t('search', 'Search'), array('class'=>'btn btn-primary', 'id'=>'submit-search', 'type'=>'submit')); ?>
but htmlButton allows you to use the glyiphicons in plain text, whilst still passing other css and options to it.
Will render a bootstrap button with chosen glyphicon in the text