Hi Sachin,
Based on your description, my understanding is that you want to make the search keywords highlighted in document preview.
By default, SharePoint uses Office Web Apps to preview the documents in search results and it does not support highlighting the keyword in document preview.
So to achieve this goal, we need to use the products which supports to highlight the keyword in document preview to integrated with SHarePoint.
The links below which introduce some products support to highlight the keyword in document preview for your references and regarding to the Arabic languages support, you may need to consult this from their side:
http://www.sharepointreviews.com/component/content/article/56-search/422-Longitude-Search-by-BA-Insight.html
http://www.surfray.com/blog/2012/07/16/document-preview-in-sharepoint-2013/
Thank you for your understanding.
Thanks,
Victoria
Forum Support
Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Subscriber Support, contact
tnmff@microsoft.com.