invoiceninja/app/Http/Requests/ClientRequest.php

<?php namespace App\Http\Requests;

class ClientRequest extends EntityRequest {

    protected $entityType = ENTITY_CLIENT;

    public function entity()
    {
        $client = parent::entity();
        
        // eager load the contacts
        if ($client && ! count($client->contacts)) {
            $client->load('contacts');
        }
         
        return $client;
    }
}