Hi,
Please configure the plugin "HikaShop products search plugin".
The last option "Fields" allow you to specify where you want to search.
Default value is : product_name,product_description
Just change it to : product_name,product_description,product_code
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.