WP_Query search for whole words

You’re gonna need regular expressions to accomplish that.

First of all, you need to change 'LIKE' to 'RLIKE' (or 'REGEXP').

Second, replace $keyword in 'value' with a regex that involves word boundaries.

Like so:

  $queryArgs = array(
    'post_type' => 'faculty',
    'posts_per_page' => -1,
    'meta_query' => array(
        'relation' => 'OR',
        array( 
            'key' => 'proposed_keywords', // name of custom field
            'value' => "[[:<:]]$keyword[[:>:]]", // matches exaclty "123", not just 123. This prevents a match for "1234"
            'compare' => 'RLIKE'
        )
    )
  );