Magento – Install Magento2 using different MySQL port

What version of MySQL are you running? In 5.6 the have_innodb check is no longer working and could cause the connection failure. See https://github.com/magento/magento2/issues/202 for details.

Adding

<protocol><![CDATA[tcp]]></protocol>

to the <connection> element should work, because in the end, any additional elements gets added to the PDO dsn string, as you can see in Zend_Db_Adapter_Pdo_Abstract::_dsn():

/**
 * Creates a PDO DSN for the adapter from $this->_config settings.
 *
 * @return string
 */
protected function _dsn()
{
    // baseline of DSN parts
    $dsn = $this->_config;

    // don't pass the username, password, charset, persistent and driver_options in the DSN
    unset($dsn['username']);
    unset($dsn['password']);
    unset($dsn['options']);
    unset($dsn['charset']);
    unset($dsn['persistent']);
    unset($dsn['driver_options']);

    // use all remaining parts in the DSN
    foreach ($dsn as $key => $val) {
        $dsn[$key] = "$key=$val";
    }

    return $this->_pdoType . ':' . implode(';', $dsn);
}

It's using a blacklist, to not add configurations that are passed differently but it doesn't restrict any other parameters. So the configuration will result in this dsn, which should work for you:

mysql:protocol=tcp;host=hostname:portnumber;dbname=pierpape_reciele