Magento 2 Short Search Keywords Optimization

There is no out of the box way of doing this, but you can trick magento into doing this.
You can create a hidden attribute called category_names that is seachable but not displayed in the frontend.
Then create an observer for the catalog_product_save_before where you take all the category names from the associated categories and place them in this field.
Something like this (untested):

public function setCategoryNames($observer)
{
    $product = $observer->getProduct();
    $categoryIds = $product->getCategoryIds();
    $storeId = $product->getStoreId();
    $categories = Mage::getModel('catalog/category')->getCollection()
                ->setStoreId($storeId)
                ->addAttributeToFilter('entity_id', $categoryIds)
                ->addAttributeToSelect('name');
    $names = array();
    foreach ($categories as $category) {
        $names[] = $category->getName();
    }
    $product->setCategoryNames(implode(' ', $names));
}

Magento by default using MySql based search. So, it is split text on word on by pattern like [^a-z0-9_]. it's why aaa-bbb interpreted as "aaa bbb"

see more details here: http://dev.mysql.com/doc/refman/5.7/en/fulltext-boolean.html