Wordpress Custom post meta meta values not saving - php

Question

I m creating a wp plugin which supports custom post type. In that i have created a custom meta box..when i enter the metabox values it will not save into the admin dashboard as well as database. Can any one help me out this.
Thanks..
//enter code here
function astestimonial_meta_box($post_id)
{
wp_nonce_field('astest_meta_box','astest_meta_box_nonce');
$clientname = get_post_meta($post->ID,'_clientname_value','true');
echo'<label for="client_name_val">';
_e('Name: ', 'astestimonial_textdomain');
echo'</label>';
echo'<input type="text" id="client_name_val" name="client_name_val" value="'.esc_attr($clientname).'" />';
}
//Save meta data code
function astest_save_client_info($post_id)
{
if(!isset($_POST['astest_meta_box_nonce']))
{
return;
}
if(!wp_verify_nonce($POST['astest_meta_box_nonce'],'astest_meta_box'))
{
return;
}
if(defined('DOING_AUTOSAVE') && DOING_AUTOSAVE)
{
return;
}
if ( isset( $_POST['post_type'] ) && 'page' == $_POST['post_type'] )
{
if ( ! current_user_can( 'edit_post', $post_id ) )
{
return;
}
}
else
{
if ( ! current_user_can( 'edit_page', $post_id ) )
{
return;
}
}
if( !isset( $_POST['client_name_val']) && !isset($_POST['client_email_val']) && !isset($_POST['client_comp_val']) && !isset($_POST['client_desig_val']))
{
return;
}
$cli_name_data = sanitize_text_field( $_POST['client_name_val'] );
update_post_meta($post_id, '_clientname_value', $cli_name_data);
}
add_action( 'save_post', 'astest_save_client_info' );