Steps to reproduce the issue

1. Create custom field (i.e. type = editor, Title = Test field, ID = 1) <= Just for easier representation.
2. Edit existing article or create new one.
3. Insert the text into the created cusom field. Use unique content (Lorem ipsum: #Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis nisi ante, bibendum id posuere eu, vestibulum sit amet ex. Sed eu diam dui. Proin pulvinar vehicula sem in ullamcorper. Cras auctor mauris mauris, in dignissim orci venenatis eget. Cras tempor mollis lacus, at gravida augue auctor eu. Nam et mi.").
4. Insert the field into the main content (I use only custom fields in the article ...).
5. Save the article.
6. Open front page / search page.
7. Enter search term "dignissin" (or any other latin word entered before).
8. Check the results.

Expected result

• The search results should contain the article that we edited/created before.
• The search results should display the Article title and the excerpt of the text, that contains the search keyword.
• The search keyword in the excerpt should be displayed differently than the text (using class "highlight").

Actual result

• The search results contains the article that we edited/created before.
• The article title is displayed and in case the keyword is in the title it is styled correctly.
• The excerpt of the text that is in the custom field is not shown.
• There is no indication the searched keyword is in that article!

System information (as much as possible)

Taken from Joomla backend:
php: Linux Humulus 4.11.11-200.fc25.x86_64 #1 SMP Mon Jul 17 17:41:12 UTC 2017 x86_64
dbversion: 5.5.5-10.1.24-MariaDB
dbcollation: utf8mb4_unicode_ci
dbconnectioncollation: utf8mb4_unicode_ci
phpversion: 7.0.21
server: Apache/2.4.27 (Fedora) OpenSSL/1.0.2k-fips PHP/7.0.21
sapi_name: apache2handler
version: Joomla! 3.7.4 Stable [ Amani ] 25-July-2017 11:11 GMT
platform: Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
useragent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:54.0) Gecko/20100101 Firefox/54.0

Additional comments

• This is the case using the simple search.
• When using smart search the results does not display empty text, but the shortcode of the custom field.
• As I am a big fan of custom fields I am using them on the whole article. All the text is entered only in custom fields, the main text field is used only to display them on the front page. In that way the content is always presented in the consistent way and it is easy to change what and how every article is displayed. But the lack of search support is a show stopper. In my case I only get a title and no text excerpt.
• I have discovered this issue after exploring significantly more bounced pageviews on search pages than before.