Express, dynamically load content on the page

My question is, I would hope, a very easy one to answer. I have a html page written in in some template/template engine(in my case its ejs).

When the user sends a get request the page is loaded and the user has a bunch of "things" he can click on to get new content. This content is delivered from a database and from a folder and I have the <%= %> fields in my .ejs file that I'm serving so that I can load in the content using an express controller. However, whenever I wish to change the content on the page (as a result of a user get request), I have to load the whole page again. I'd like to only load the new/changes <%= > fields from the ejs template.

I'd prefer to do this whole process server side OR if I am to include files for this on the users side I'd prefer to limit myself to some simple javascript or changes in my HTML and not go through the whole process of integrating Angular or React with my application.