This is intended for use with “incremental search” systems, which don’t wait for the user to finish typing their search before displaying an initial set of results. For example, in such a system a user would start typing the query and the system would immediately display a new set of results after each letter keypress, or whenever the user pauses for a short period of time (or some other similar strategy).
This allows for prefix matches, matching any number of trailing characters, so,
"_partial": "wildc" or
"wildc*" would match wildcard,
wildcarded, wildcards, wildcat, wildcats, etc.
This is a bit different from Wildcard Query. Partial is intended for “incremental search”.
Using the suffix
** is equivalent to use