Symfony2 createQuery returns no line because of join which return null

Question

I have a simple query

$query = $em->createQuery(''
            . 'SELECT  c.id, c.firstname, c.lastname, coun.country '
            . 'FROM OandPboBundle:Clients c '
            . 'JOIN OandPboBundle:Countries coun WITH coun.id = c.country '
            . 'WHERE c.id = ?1'
            )
                ->setParameter(1, $id)
                ->setMaxResults(1);
    $result = $query->getResult();

As you see it's a Clients entity with a onetoone relation with a Countries entity. So I have a country_id field in my clients table. But the country is a null field, country is not required so the country_id field may be NULL.

So when I execute my query, the query returns NO LINE when there is no country (NULL). Because the left join doesn't exist. And it returns a line of course when there is a country.

How can I do, so the query returns a CLIENT row even if there is no country?

Thank you everybody by advance

In case of I put the CLIENTS entity

class Clients
{
    /**
     * @ORM\OneToOne(targetEntity="OandP\boBundle\Entity\Countries", cascade={"persist"})
     * @ORM\JoinColumn(nullable=true)
     */
    private $country = null;


    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;
}

And the COUNTRIES entity

class Countries
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @var string
     *
     * @ORM\Column(name="code", type="string", length=2)
     */
    private $code;

    /**
     * @var string
     *
     * @ORM\Column(name="country", type="string", length=255)
     */
    private $country;