WP_Query - Order results by meta value

Question

I've checked around and haven't seen an answer which works as of yet. I have a WP_Query with the following arguments:

$args = array(
    'post_status' => 'publish',
    'post_type' => 'listing',
    'meta_key' => 'client_feedback_score',
    'orderby' => 'client_feedback_score',
    'order' => 'DESC'
);

$query = new WP_Query($args);

I want to order the results by the custom post field client_feedback_score, lowest to highest. But this doesn't seem to work... can anyone point me in the right direction?

EDIT (SOLVED):

Thanks to Milo's response, here's the working code for ordering by a numerical meta value:

$args = array(
    'post_status' => 'publish',
    'post_type' => 'listing',
    'meta_key' => 'client_feedback_score',
    'orderby' => 'meta_value_num',
    'order' => 'DESC'
);

Answer 1

orderby should be meta_value_num, or meta_value, not the name of the key. See WP_Query orderby parameters.

Answer 2

if your meta value is not numeric for example if it is a date value; than you can add parameter meta_type => DATE. Possible values are; 'NUMERIC', 'BINARY', 'CHAR', 'DATE', 'DATETIME', 'DECIMAL', 'SIGNED', 'TIME', 'UNSIGNED'.

Query with meta type will be like that:

$args = array(
'post_status' => 'publish',
'post_type' => 'listing',
'meta_key' => 'client_feedback_score',
'orderby' => 'meta_value_num',
'meta_type' => 'DATE',
'order' => 'DESC'
);