How to save only specific attribute value rather than saving the whole product in Magento2

Its the same as Magento 1

$dataobject->setData('attribute_code', $value);
$dataobject->getResource()->saveAttribute($dataobject, 'attribute_code');

This will work for any entity.

As per @Raphael's Answer It will not work for sales attributes.

Basically it calls Magento\Eav\Model\Entity\AbstractEntity::saveAttribute() function.

This will accept two parameters

saveAttribute(\Magento\Framework\DataObject $object, $attributeCode)

First to be $object is an object which needs to be updated and second parameter will be $attributeCode which is the code for the attribute to be updated.

Just to clarify Jaimin's answer:

This will work for any entity.

This is not true. It will only work for EAV entities which extend Magento\Eav\Model\Entity\AbstractEntity

If you're dealing with a non EAV entity where the resource model extends Magento\Framework\Model\ResourceModel\Db\AbstractDb you will have to implement the saveAttribute method in your resource model.

In Magento 2, they have done it for the Magento\Sales\Model\ResourceModel\Attribute class:

public function saveAttribute(AbstractModel $object, $attribute)
{
    if ($attribute instanceof AbstractAttribute) {
        $attributes = $attribute->getAttributeCode();
    } elseif (is_string($attribute)) {
        $attributes = [$attribute];
    } else {
        $attributes = $attribute;
    }
    if (is_array($attributes) && !empty($attributes)) {
        $this->getConnection()->beginTransaction();
        $data = array_intersect_key($object->getData(), array_flip($attributes));
        try {
            $this->_beforeSaveAttribute($object, $attributes);
            if ($object->getId() && !empty($data)) {
                $this->getConnection()->update(
                    $object->getResource()->getMainTable(),
                    $data,
                    [$object->getResource()->getIdFieldName() . '= ?' => (int)$object->getId()]
                );
                $object->addData($data);
            }
            $this->_afterSaveAttribute($object, $attributes);
            $this->getConnection()->commit();
        } catch (\Exception $e) {
            $this->getConnection()->rollBack();
            throw $e;
        }
    }
    return $this;
}

In the case of product, you can use the mass action object. For example:

// Edit
$productIds = [123];
$attributesData = ['name' => 'new product name'];
$storeId = 0;
$productMassAction = \Magento\Framework\App\ObjectManager::getInstance()->get('Magento\Catalog\Model\Product\Action');
$productMassAction->updateAttributes($productIds, $attributesData, $storeId);