$collection->addAttributeToFilter('attributename', array('is' => null));
$collection->addAttributeToFilter('attributename', array(115,116));

$collection->addAttributeToFilter(
    array(
        array(
            'attribute' => 'name_of_attribute_1',
            'null' => 'this_value_doesnt_matter'
        ),
        array(
            'attribute' => 'name_of_attribute_2',
            'in' => array(115, 116)
        )
    )
);

var_dump(
    Mage::getModel('catalog/product')
    ->getCollection()
    ->addFieldToFilter(
        array(
            array(
                'attribute' => 'description',
                'null' => 'this_value_doesnt_matter'
            ),
            array(
                'attribute' => 'sku',
                'in' => array(115, 116)
            )
         )
     )
     ->getSelectSql(true)
 );

SELECT
    `e`.*,
    IFNULL(_table_description.value, _table_description_default.value) AS `description`
FROM
    `catalog_product_entity` AS `e`
INNER JOIN
    `catalog_product_entity_text` AS `_table_description_default` ON
    (_table_description_default.entity_id = e.entity_id) AND
    (_table_description_default.attribute_id='57') AND
    _table_description_default.store_id=0
LEFT JOIN
    `catalog_product_entity_text` AS `_table_description` ON
    (_table_description.entity_id = e.entity_id) AND
    (_table_description.attribute_id='57') AND
    (_table_description.store_id='1')
WHERE (
    (IFNULL(_table_description.value, _table_description_default.value) is NULL) OR
    (e.sku in (115, 116))
)

$collection->addAttributeToFilter('attribue_name', array('or'=> array(
             0 => array( 'neq' => '1'),
             1 => array('is' => new Zend_Db_Expr('null')))
         ), 'left');
IT's working.

$collection->addAttributeToFilter(
    array(
        array('attribute' => 'name_of_attribute_1','null' => 'this_value_doesnt_matter'),
        array('attribute' => 'name_of_attribute_2','in' => array(115, 116))
        )
     '',
    'left'
);