cmb2 field type : file is not displaying image on front end?

By using cmb2 field type => file, In backend image file was uploaded but in front end it’s not displaying, I checked with inspect element and in that found image src unknow, Please help

Here is my code

// Client Section Shortcode

add_shortcode('client-section','home_client_section_shortcode');

function home_client_section_shortcode($attr,$content){

     $client =  extract(shortcode_atts( array(
        'title'     => 'Oue Clients',
        'subtitle'  => 'Some of the best.'

      ), $attr) );

  ob_start(); ?>

    <section>
      <div class="container">
        <div class="title center">
          <h4 class="upper"><?php echo $subtitle; ?></h4>
          <h3><?php echo $title; ?><span class="red-dot"></span></h3>
          <hr>
        </div>
        <div class="section-content">
          <div class="boxes clients">

            <?php 

             $client = new WP_Query( array(
                'post_type'       => 'agro-client',
                'posts_per_page'  => 10

              ));

              $logo =  wp_get_attachment_image( get_post_meta( get_the_id(),'_client-logo', true),'medium' );

              while($client->have_posts()): $client->the_post(); 
             
               
              ?>
              

                 <div class="col-sm-4 col-xs-6 border-right border-bottom">

                   <img src="<?php echo $logo; ?>" alt="" data-animated="true" class="client-image">

                 </div>

              
            <?php endwhile; ?>

          </div>
        </div>
      </div>
    </section>

  <?php return ob_get_clean();
}

cmb2 codes here

// Home Client Section meta box

	$client= new_cmb2_box( array(
		'title'	 => ' Client Logo Upload Fields',
		'id'	 => 'client_fields',
		'object_types'	=> array('agro-client')

	));

	$client-> add_field( array(
		'name'	=> 'Upload Client Logo',
		'id'	=> '_client-logo',
		'type'	=> 'file',
		'options' => array(
		'url' => false, // Hide the text input for the url
		),
		'text'    => array(
		'add_upload_file_text' => 'Add or Upload Logo' // Change upload button text. Default: "Add or Upload File"
		),

	));