The functionality you are after is called query truncation and is no longer supported by Funnelback's default query processing mode.
When working in the old term at a time mode this is supported via the * operator. Document at a time mode which is the current (and recommended) default does not support this, however a workaround is available to implement partial support for this.
See: https://community.funnelback.com/knowledge-base/implementation/query-processing/query-language/adding-limited-wildcard-support-to-daat-mode
It is not recommended to switch to the legacy term at a time mode as a number of newer features will cease to function when this mode is enabled. Also, legacy truncation is a very expensive operation and can result in a large hit to the search performance.